The type of corner joint that I am concerned with comprises a metal core having projecting arms that are covered by a layer of plastic material. These plastic-covered arms fit tightly into tubular metal components, thus forming a framework portion in which the tubular components are connected together through the corner joint. The metal core imparts mechanical strength to the corner joint, and the plastic covering enables a tight fit to be developed between the corner joint and the tubular metal components when the tubular components are pushed onto the arms of the corner joint during assembly of the framework.
Prior designs of these corner joints have not been as rigid and sturdy as is sometimes desired. Another problem with prior designs is that the plastic covering cannot readily be replaced should it become damaged as a result of abrasion, cutting, or deformation during assembly or disassembly of the framework. Such damage can interfere with reassembly of the framework and with achieving the desired tight fit with the tubular metal components upon reassembly.